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Abstract: SA-PO329

T Cell-Mediated Immune Rejection of B2M Knockout Induced Pluripotent Stem Cell (iPSC)-Derived Kidney Organoids

Session Information

Category: Development, Stem Cells, and Regenerative Medicine

  • 600 Development, Stem Cells, and Regenerative Medicine

Authors

  • Van den Berg, Cathelijne W., Leids Universitair Medisch Centrum, Leiden, Netherlands
  • Gaykema, Lonneke, Leids Universitair Medisch Centrum, Leiden, Netherlands
  • van Nieuwland, Rianne Yvon, Leids Universitair Medisch Centrum, Leiden, Netherlands
  • Lievers, Ellen, Leids Universitair Medisch Centrum, Leiden, Netherlands
  • de Klerk, Juliette A., Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
  • Dumas, Sébastien J., Leids Universitair Medisch Centrum, Leiden, Netherlands
  • Kers, Jesper, Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
  • Zaldumbide, Arnaud, Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
  • Rabelink, Ton J., Leids Universitair Medisch Centrum, Leiden, Netherlands
Background

“Stealth” induced pluripotent stem cell (iPSC)-derived kidney organoids represent an attractive strategy and could potentially be used in clinical transplantation. Genetic modification of the human leukocyte antigen (HLA) class I molecules in iPSCs prior to transplantation of their derived tissues could prevent immune rejection. Here we evaluated the effect of β2-microglobulin (B2M) knockout on T cell-mediated rejection of iPSC-derived kidney organoids.

Methods

Specific genetic modification achieved by CRISPR-Cas9 was used to knockout B2M gene expression and prevent HLA class I surface expression on iPSCs. Kidney organoid immunogenicity was determined in vitro by coculture with alloreactive T cells and in vivo following transplantation in humanized mice.

Results

We found that iPSC-derived B2M-/- kidney organoids were protected from T cell rejection in vitro. To evaluate in vivo protection, unmodified (control) and B2M-/- kidney organoids were transplanted in humanized mice that were engrafted with human peripheral blood mononuclear cells (PBMCs). Successful engraftment of the human PBMCs was validated and 4 weeks after PBMC injection we observed the infiltration of CD4+ and CD8+ T cells in the kidney organoids. There was no difference in the infiltration rate of CD4+ and CD8+ T cells, proliferation of T cells and T cell cytotoxicity between control and B2M-/- organoids. Control and B2M-/- organoids tissue integrity was similarly affected, showing tubulitis and loss of tubule integrity. Although the B2M-/- organoids were unable to express HLA class I on the cell surface, we found increased expression of HLA class II in control and B2M-/- organoids that were transplanted in mice with human PBMCs. HLA class II expression was expressed not only by endothelial, but also epithelial cells of the kidney organoid, posing an additional immunological barrier to the transplantation.

Conclusion

We conclude that knockout of the B2M gene alone is not enough to protect iPSC-derived kidney organoids from T cell mediated immune rejection and highlight the importance of HLA class II signalling in the graft rejection process.